1. Field of the Invention
The invention relates to a power output apparatus, a control method thereof, and a vehicle equipped with the power output apparatus.
2. Description of the Related Art
Japanese Patent Application Publication No. 6-93911 (JP-A-6-93911), for example, discloses a power output apparatus that is installed in a vehicle and executes Idle Speed Control (ISC) learning processing for holding an idle rotation speed of an internal combustion engine at a target rotation speed during throttle valve opening/closing control, which is performed using a value obtained by correcting a detection value from a throttle opening sensor in accordance with a valve opening correction value relating to a throttle valve provided in an internal combustion engine after the valve opening correction value has been updated under a condition such as a vehicle speed value of 0. This processing is performed in the apparatus in an attempt to obtain an appropriate learning rate.
In a power output apparatus having an electric motor connected to a drive shaft, in which the drive shaft, an output shaft of an engine, and a rotary shaft of a generator are connected by a planetary gear mechanism or the like, a control amount such as a throttle opening during an idle operation of the engine is learned when power is not output to the drive shaft, but in order to secure more learning opportunities, learning may also be performed when power is output to the drive shaft from the electric motor alone. When a rotation speed of the drive shaft increases, however, the control amount during the idle operation may be learned erroneously due to the effect of the increased rotation speed on the output shaft of the engine.